For more than 40 years, the South Carolina Autism Society has provided valuable assistance to families. Now, the parent-led organization is reeling from a state investigation that found fraudulent activity at the Society's highest levels.

"Between state and federal dollars, we could be talking as much as $500,000 that is currently unaccounted for," Jay W. Ragley, former spokesman for the South Carolina Department of Education, told News 4's Tim Waller.

SCDE was the first to notice accounting problems with the Society's accounting. In an April 12, 2013 letter to the Senate Finance Committee, State Superintendent Mick Zais asked for "no transfer of funds to the South Carolina Autism Society until the South Carolina inspector general has completed its investigation into the financial records of this entity."

The investigation found a mountain of problems.

The 12-page report, titled "Fraudulent Activity at a Non-Profit Organization Involving State Funds" found $462,060 in taxpayers money was "unaccounted for." And officials discovered the former president of the South Carolina Autism Society, Craig Stoxen, had "shredded a large volume of documents," which the inspector general noted, "was unusual activity for him."

The OIG also discovered the Society "submitted false grant expense reimbursements" to the Dept. of Education and S.C. Developmental Disabilities Council, "which resulted in $188,819 in reimbursement requests exceeding the Society's actual expenses."

Then, there was the issue of credit card fraud. According to the report, the Society's former bookkeeper and Director of Finance, Mary Bennett, "stole $5,771.02 by improperly using the Society's business credit card for personal benefit." The report went on to say the State Inspector General would present the facts to the State Solicitor's Office for a "potential prosecution."

But WYFF News 4 Investigates has learned that Bennett, who was later fired, has never been charged. She reportedly reimbursed the Society approximately $3,000, but officials could find no record she had paid back the remainder of what she owed, according to the OIG report.

In February, as the investigation continued, Stoxen, the organization's president, took his own life.

"I was very shocked when all of this came up," said Susan Kastner, board chair for the S.C. Autism Society, in the organization's first television interview since the OIG report was released. "There are so many things we don't have answers to. At this point, we're working with OIG and other agencies to find answers."

Kastner said the S.C. Autism Society Board wasn't aware of any problems until the State Department of Education began asking questions and cut off funding.

"We thought (Stoxen) was doing a good job," Kastner said. "Programs were growing. More families were getting served. We looked at the annual report every year. The annual reports got clean audits."

She said the board was aware its bookkeeper had made personal charges using the Society's business credit card.

"Why wasn't she prosecuted?" Waller asked.

"I think we were content that she had reimbursed the money and had been terminated," Kastner said.

Waller asked Kastner if she worried about the public's loss of faith in her organization in the wake of the state investigation.

"We do worry somewhat about a loss of faith," she said. "I hope families that know a lot about us will know that they know us and that we can keep their faith, because we also are parents."

In August, the S.C. Autism Society was forced to suspend its most popular program. The Parent to School Partnership, which employed parent mentors to provide free support to families at IEP meetings, was shut down , because SCDE withheld the Society's August payment.

"SCAS is not in a position to provide parent mentor services without these funds as reimbursement," Interim President Kim Thomas wrote in the organization's newsletter.

SCDE spokesperson Laura Bayne said state funding for the program will not be restored until the Society can provide documentation on $462,060 in unaccounted for funds.

"We are expecting documentation by the end of (September)," Bayne said. "We will not know whether that will resolve the outstanding issues until we receive the information."

What happens next could have a major impact on autistic children across the state.